Biliary Stents are Associated with Increased Risk of Liver Abscess after Traumatic Liver Injury

Authors:
Anna Huang Perez, Henry Olivera Perez, Andrea Gochi, Adam Gutierrez, Genna Beattie, Naveen Balan, Lucas Thornblade, Gregory Victorino, April Mendoza

Body of Abstract:
Background

Liver abscess is a rare but highly morbid complication of traumatic liver injury. Many patients who develop a liver abscess have previously undergone biliary instrumentation leading to colonization of the biliary tract. We hypothesized that the use of biliary stents will be associated with greater risk of liver abscess after traumatic injury independent of surgical or angiographic intervention. We also sought to determine other risk factors for liver abscess after traumatic injury.

Methods

A retrospective review of adult patients presenting to a single level 1 trauma center with an American Association for the Surgery of Trauma (AAST) grade 3 or higher liver injury between 2017— 2025 was performed. Patient characteristics and outcomes were collected from the electronic medical record. Univariable and multivariable analyses identified risk factors and predictors of liver abscess.

Results

Two hundred and eighteen patients met inclusion criteria, of which 160 (73%) were male and 121 (56%) presented after blunt trauma. The median age was 31 years. Eighty-four patients (39%) underwent laparotomy, 28 (13%) underwent hepatic angioembolization, 16 (7%) underwent both interventions, and 122 (56%) did not undergo either intervention. Twenty-four patients (11%) developed a bile leak and 15 (7%) underwent common bile duct (CBD) stent placement. Sixteen patients (7%) developed a liver abscess and were treated with antibiotics for a median of 14 days post abscess diagnosis. Among the 12 patients who underwent either percutaneous or surgical drainage, Enterococcus faecalis was the most common organism that speciated (n=3).

On univariate analysis, risk factors for liver abscess were penetrating trauma (14% abscess rate in penetrating patients vs 2% abscess rate in blunt patients, p<0.001), bile leak (46% vs 3%, p<0.001), CBD stent (67% vs 3%, p<0.001), angioembolization (18% vs 6%, p=0.04), and laparotomy (18% vs 1%, p<0.001). In this sample, grade of liver injury, Injury Severity Score, and 24-hour packed red blood cell transfusions were similar between abscess and non-abscess patients. On multivariate analysis, CBD stent placement (OR 22, p=0.01) and laparotomy (OR 13, p=0.03) were independently associated with liver abscess. Conclusions These findings suggest that CBD stenting is associated with liver abscess after traumatic liver injury independent of other risk factors such as bile leak and angioembolization. Further studies may be warranted to investigate the effect of periprocedural antibiotics on the risk of liver abscess in patients who undergo biliary stenting after traumatic liver injury.

Cefazolin for All: Improving Surgical Infection Prevention Through Safe Antimicrobial Stewardship

Authors:
Yeshwanth Vedire, Drishti Lall, Mohammad Maki, Abigail Ruby, Eman Chami, Anita Shallal, Arielle Hodari Gupta

Body of Abstract:
Introduction: Surgical site infections (SSI) account for almost 20% of all hospital acquired infections, increase hospital length of stay by nearly 10 days and increase cost by $20,000 per admission. There is a reported 50% increase in SSI rate in patients with reported penicillin allergies due to the use of alternative non-beta-lactam antibiotics instead of cefazolin, despite evidence on consensus guidelines suggesting its safety in these cases. We sought to describe the impact of an educational campaign to improve cefazolin prescribing for surgical infection prophylaxis (SIP) at our institution.

Methods: This was an IRB exempt, single pre-test, post-test quasi-experiment at our single institution in southeast Michigan. Beginning in late February 2025, interventions included revising surgical order sets to clearly state cefazolin safety in penicillin allergic patients, updating institutional guidelines for both allergy and SIP to restrict alternative non-beta-lactam antibiotics to cases of type IV mediated hypersensitivity reactions  (ie; severe cutaneous adverse reactions [SCAR] such as Steven Johnson Syndrome [SJS[, Toxic Epidermal Necrolysis [TEN], Drug Reaction with Eosinophilia and Systemic Symptoms [DRESS], Acute Generalized Exanthematous Pustulosis [AGEP]), modifying electronic medical records of documented allergies to more clearly delineate severity and separate rash from SCAR, and creation of a cefazolin prescribing dashboard to monitor trends. An extensive educational campaign was launched, featuring interactive materials, QR-accessible slides with knowledge checks, educational flyers, and default workstation screensavers in preoperative areas. Additionally, anesthesia, surgical and orthopedic grand rounds reinforced education and promoted practice change.  The primary endpoint was the proportion of outpatients receiving cefazolin for NHSN procedures (colectomies, hysterectomies, C sections, spinal fusions, hip and knee arthroplasties) in the pre-intervention (Sept 2024-Feb 2025) and post-intervention (April 2025-Sept 2025).

Results: 62.6% of patients received cefazolin in the 6 months preceding the intervention compared to 70.2% on average in the 6 months after, representing an absolute increase of 7.6%. This improvement in cefazolin compliance is observed in outpatient surgeries (84.3% vs. 93.4%) and admissions following a surgery (68.8% vs. 79%). Despite an increase in cefazolin use, there was no significant decrease in SSI rate since project implementation (2.7% vs. 2%).

Conclusion: By using a combination of EMR order sets, extensive educational campaigns, and visual reminders, we have shown that the “Cefazolin for All” campaign improved cefazolin use, promoting evidence-based practices and improving surgical infection prevention and antimicrobial stewardship.  Although a significant decrease in SSI rate has not yet been observed, ongoing monitoring to evaluate the long term impact on patient outcomes is needed.

A burn injury model using an ex vivo biologically active human skin platform: examples of limitations of novel alternative methods (NAMs) and compensatory insights from computational modeling

Authors:
Gary An, Chase Cockrell

Body of Abstract:
Background: Novel alternative methods (NAMs) are microphysiological systems (MPS) that use human-derived cells intended to reduce and potentially replace animal models. It is still an open question as to whether MPSs can reproduce the organismal/system-level complexity seen in clinical disease. In silico methods have been proposed as a way of integrating multiple MPSs; we have previously described a modular architecture using agent-based models to provide this capability. We apply this concept to modeling the burn patient, and herein propose to use an ex vivo biologically active human skin model sourced from GenoskinTM  to generate experimental data to calibrate a previously developed modular component, the Burn Agent-based Model (BABM), of our Burn Digital Twin.

Methods: Burn wounds were induced on Genoskin TM Hyposkin modules (2 cm diameter) using a 25 W contact wood burning tool with a 1 cm diameter flat tip preheated to between 200 °C and 300 °C. The four experimental groups (n = 3/group) were: control, 5 s contact, 15 s contact and 30 s contact. Hyposkin modules were cultivated in an incubator (37 °C, 5 % CO2, 95 % humidity) for 7 days with daily renewal of support medium with exchanged media sent for Luminex analysis of the following mediators: TNF, IL1a/b, IL1RA, IL4, IL6, IL8, IL10, IL12, IFNg and GCSF. Tissue at the end of the experiment (Day 7) was sent for tissue Luminex and histology. Experimental data was used to calibrate our previously developed Burn Agent Based Model using our Active Learning Pipeline/Model Rule Matrix

Results: Histological analysis demonstrated reproducible burn injuries with 5 s burns = superficial partial thickness (SPT) burns, 15 s burns = deep partial thickness (DPT) burns and 30 s burns = full thickness (FT) burns. In terms of trajectories of measured cytokines in the support media, TNF levels peaked at 24 hrs and subsequently decreased, IL1a and IL12 plateaued at 24 hrs and were sustained, IL1b peaked at 48-72 hrs and subsequently decreased, IL1a, IL4, IL6, IL10 and IFNg plateaued at 48 hrs and were sustained, IL1RA rose until Day 5 then decreased, and IL8 and GCSF rose throughout the experiment. There were no statistical differences in the media mediator levels based on duration/depth of burn, though tissue levels of IL1a, IL1b, IL10, IL12 and GCSF were highest in the 5 s/SPT burns. Calibration of the BABM to this data required exclusion of systemic perfusion/circulating inflammatory cells to render it insensitive to burn depth. 

Conclusion: We produced SPT, DPT and FT contact burns in an ex vivo human skin model, but had the counter intuitive result that increasing burn depth and amount of tissue damage did not manifest in increased mediator levels. Calibration of the BABM required exclusion of circulating inflammatory cells, suggesting an avenue by which computational experiments can provide direction to overcoming the limitations of a NAM in representing systemic disease.

A critical review of 1113 isolates of non-fermentative Gram-negative rods isolated from 794 patients at a rural hospital

Authors:
Hugo Bonatti, Saron Araya, Yohana Araya, Pooja Ajith, Pathya Kunthy, Sridha Gona, Stephen Kavic, Aaron George

Body of Abstract:
Background: Non-fermentative Gram-negative rods derive their name from the inability to use glucose as energy substrate. This diverse group of organisms are found in various natural specimens such as soil; moist environments are their preferred habitat. Pseudomonas aeruginosa is the most common human pathogen in this group with Stenotrophomonas maltophilia, Acinetobacter spp, Alkaligines spp, Achromobacter spp and Moraxella spp amongst many others being important members. They may cause a variety of diseases including soft tissue, urinary tract, respiratory tract and blood stream infections, which may be difficult to treat due to natural antibiotic resistance and rapid development of resistance during treatment.

Methods: Our institutional database was searched for all surgical and blood stream infections caused by non-fermenters during a 4-year period and the most common pathogens were compared to each other.

Results: In total 1113 isolates in 792 patients were identified. Table 1 shows demographic, clinical and microbiology data for the most common pathogens. Pseudomonas aeruginosa (n=850) outnumbered all others; various non-aeruginosa Pseudomonas spp accounted for 35 isolates. More common pathogens were Acinetobacter spp (n=72), Stenotrophomonas maltophilia (n=57) and Alcaligines faecalis (n=40) followed by Moraxella spp (n=110, Achromobacter spp (n=11), Myroides spp (n=10) and Roseomonas spp (n=70. Shewanella spp, Brevundimonas spp, Kocuria spp, Comamonas spp, Delftia spp, Sphingomonas spp, Chryseobacterium spp , Aggregatibacter spp, Trueperella spp and Ochrobactrum anthropic were identified in <5 cases. Median patient age ranged from 60 to 66 years; approximately 55% were male. Median BMI was 32.5kg/m2 in non-aeruginosa Pseudomonas spp patients and 25.9kg/m2 Acinetobacter spp patients. 61% of patients with Alcaligines faecalis infections were active smokers as opposed to 23%-29% for all other pathogens resulting in highest rates of COPD and CAD in the Alcaligines group. Acinetobacter, Stenotrophomonas and Alcaligines infections were more commonly polymicrobial (approximately 70%) than Pseudomonas infections (approximately 50%); in all groups, staphylococci were the most common co-pathogens. Acinetobacter and non-aeruginosa Pseudomonas spp invaded the blood stream in 30% versus 10% (others); soft tissue infections of the lower extremity were in all groups the most common clinical manifestation whereas intraabdominal infections accounted only for 3% to 13% of cases. Survival after 2 years was 91% in patients with Acinetobacter spp infections but only 73% in the Alcaligines  group. Conclusion: Pseudomonas aeruginosa remains the most common non-fermenter (almost 75% of cases). Significant differences between the various groups regarding demographics, clinical and microbiology parameters studied were found. The high rate of natural antibiotic resistance makes treatment challenging; for surgical infections source control is of utmost importance.

A Race Against Time: Early vs Late Infection After Severe Trauma

Authors:
Amin Dehghan, Marina Eguchi, Fabiana Sanchez, Marco Henriquez, Ricardo Fonseca, Melissa Canas, Grant V. Bochicchio

Body of Abstract:
Introduction: Infections are a significant source of morbidity and prolonged hospitalization among severe injured trauma patients. When an infection is suspected or diagnosed (early versus late) may reflect distinct pathophysiologic mechanisms, patient factors, and injury patterns, influencing outcomes and management strategies. Our goal was to describe the incidence and compare characteristics of early vs. late infection based on when infection was suspected in a Level 1 trauma cohort.

Methods: We retrospectively analyzed a prospectively trauma registry on Level I trauma patients (2019–2024) with de-identified patient data. Collected variables included demographics, comorbidities, injury mechanism, clinical severity (ISS, GCS, APACHE II), MTP activation and blood products transfusion, airway interventions, and infection data. The blood transfusion score was calculated: whole blood units ×2 plus packed RBC, FFP, TXA, platelets, and cryoprecipitate units ×1. Time to infection was measured from ED arrival. Descriptive statistics summarized characteristics; t-tests and chi-square tests compared groups.

Results: Among 599 Level 1 trauma patients, 102 (17%) were diagnosed with infection. Based on a median 90-hour interval to initial suspicion, infections were classified as early (51, 50%) or late (51, 50%). Pneumonia had a median onset of 87 [20–160] hours, UTI 77 [12–211] hours, and other infections 140 [12–251] hours post-admission (Fig. 1).

The mean age was significantly higher in the early infection group (52.8 ± 21.1 vs 40.5 ± 18.0 years, p = 0.002) and the mean ISS was significantly higher in the late infection group (27.4 ± 13.6 vs 20.1 ± 12.6, p = 0.022); While GCS (10.5 ± 5.3 vs 10.7 ± 5.2, p = 0.89), blood transfusion score (6.5 ± 11.5 vs 9.9 ± 12.0, p = 0.15), and APACHE II score (18.7 ± 8.3 vs 19.8 ± 9.5, p = 0.54) did not differ. In the patients with late infection, MTP activation rate and substance use disorder were more common (39.2% vs 19.6%, p=0.03, 72.5% vs 51.0%, p=0.025, respectively). There were no significant differences in race (p = 0.10), sex (p = 0.097), prehospital airway intervention (p = 0.562), ED airway intervention (p = 0.282), NPPV use (p = 1.0), or mechanism of injury (penetrating, blunt, burn; p = 0.057).

Gram negative pathogens were more common in the late infection (61.5 % vs 41.8%, p=0.046).  Early infections included 15 Gram-positive, 18 Gram-negative, 7 viral, and 3 fungal cases, while late infections included 13 Gram-positive, 24 Gram-negative, and 2 fungal cases. Although the pseudomonas infection rate was higher in late infections (15.4% vs 4.7%), it was not statistically significant due to sample size (p = 0.142).

Conclusion: In critically injured level 1 trauma patients, one should be highly suspicious and on alert for the diagnosis of early infection. Also, the clinical team should remain alert for Gram-negative infections, particularly after 90 hours.